Track-type or crawler-type machines may be employed in construction, mining, oil, gas, and forestry operations, and in other rugged operating environments. These machines employ tracks which engage the ground and enable the machine to move about and over relatively rough terrain. Typical track designs include a track pin, either rotatably engaged or fixed to a pair of track chain assemblies, and a bushing rotatably positioned between the track chain assemblies. The tracks may operate in adverse environments in which track joints may be exposed to various abrasive mixtures of water, dirt, sand, rock, and/or chemical elements and to wide temperature ranges varying from high heat in deserts to extreme cold in arctic regions. Seals may be placed in the track joints in a variety of configurations and positions to ensure that contaminants are effectively excluded and lubrication effectively retained.
Over the course of many hours of operation, the constant contact among the moving track components may result in significant wear, even where bearings and lubricating oil are used to reduce friction among the components. Galling and other wear related problems tend to be particularly prevalent with relatively large track-type machines, which may subject the track components to substantial loads. In particular, wear and galling of the seals and the track pins are problematic.
One method for improving the component life of track components is described in U.S. Pat. No. 6,206,491 (the '491 patent) to Hisamatsu, issued on Mar. 27, 2001. The '491 patent describes a crawler device comprising a pin and a stationary bush for connecting a right row of crawler links and a left row of crawler links, and a rotating bush outwardly fitted to the stationary bush in a freely rotatable manner. Support members are inserted to the right and left rows of the crawler links, a first seal is inserted between an outer end portion of each of the support members and the opposing crawler links, and a second seal is inserted between an inner end portion of each of the support members and both end portions of the opposing rotating bushes. A clearance of the first and second seals can maintain the initial value at assembly against an external force during an operation. The lubricating oil is sealed in the pin and does not leak from the first and second seals, so that the durability of the seals and crawler device are improved.
Although the crawler device of the '491 patent may improve the durability of some components of the crawler device, it may have limitations. For example, the first and second seals may still undergo wear even in the presence of lubricating oil. Contact between the seals and the crawler links may eventually wear down the seals, resulting in costly repairs and replacements.
The track assembly of the present disclosure is directed towards improvements to the existing technology.